Find force from a function of displacement?

[beanryu]

An object with mass m moves along the x-axis. Its position as a function of time is given by x(t)=At-Bt^3, where A and B are constants. Calculate the net force on the object as a function of time.

I have no idea as to how to begin.
Thanks for anyone's help.
:confused: I dont know !&@#%^@%!$^$(! about doing this kind of calculus problem.

But I see some correlation between this function and the formula X=X+vt+1/2at^2

[M.Hamilton]

But I see some correlation between this function and the formula X=X+vt+1/2at^2

Well don't over complicate the problem, F=ma right? Now all you have to do is figure out how to get from position to acceleration. Hope that helps.

Merle